Field of the Invention
The present invention relates to an electrostrictive element manufacturing method.
Description of the Related Art
Conventionally, a dielectric structure having a film electrode on a dielectric film formed of a PZT insulating film is known. Such dielectric film and film electrode are formed by patterning (see Japanese Patent Laid-Open No. 2008-4572, for example).
On the other hand, it is known that when an electrode is connected to front and rear both faces of a dielectric film formed of elastomer to apply a voltage, the dielectric film receives a compression force by Maxwell stress (inverse piezoelectric effect) by interfacial polarization caused by electrostatic power so that the dielectric film contracts in a thickness direction and stretches in a lateral direction (a direction orthogonal to the thickness direction). Recently, an electrostrictive element that includes a dielectric film and an electrode and drives in accordance with the aforementioned principle has been considered.
As an electrostrictive element having a dielectric film formed of elastomer, an electrostrictive element having a film electrode that is disposed on front and rear both faces inside an outer peripheral edge of the dielectric film and is expandable and contractible following extension and contraction of the dielectric film, and a frame that is disposed on an outer peripheral edge of one face of the dielectric film and keeps the dielectric film in a stretched state has been proposed (see Japanese Patent Laid-Open No. 2003-174205, for example).
In the electrostrictive element, when a positive or negative voltage is applied to the respective film electrodes through a collector, the dielectric film contracts in the thickness direction and stretches in the lateral direction. However, since the frame holds the outer peripheral edge of the dielectric film, outward stretching of the dielectric film is regulated and the dielectric film stretches inward. The dielectric film has an approximately mountain-like shape as a whole with a protrusion at one face side. Subsequently, the shape of the stretched dielectric film is almost restored by cancellation of the voltage application.
The film electrode is desired to have not only conductivity but also excellent elasticity to follow a stretching behavior of the dielectric film without interfering with the dielectric film stretching.
Therefore, it is conceived that in the electrostrictive element including the dielectric film formed of elastomer, the film electrode is formed by masking the dielectric film held in the stretched state and patterning a conductive material by spray coating, etc.
However, to form the film electrode having a uniform thickness by the spray coating, etc. for ensuring excellent conductivity, there is a problem that it is difficult even for a highly skilled engineer to make the film electrode thin due to flexibility or adherence of the film electrode itself. If the film electrode is thick, the elasticity cannot be ensured. Thus, the film electrode may fail to follow the stretching behavior of the dielectric film, resulting in interfering with stretching of the dielectric film or damaging the film electrode itself.
In view of the aforementioned circumstance, the object of the present invention is to provide a method of manufacturing an electrostrictive element in which the electrostrictive element having an expandable and contractible film electrode having a thin and uniform thickness can be easily formed.